Synthesis and Luminescent Properties of LaAlO3:RE3+ (RE = Tm, Tb) Nanocrystalline Phosphors via a Sol—Gel Process

LaAlO 3:Tm 3+ and LaAlO 3:Tb 3+ phosphors were prepared through a Pechini-type sol−gel process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence, and cathodoluminescence (CL) spectra were utilized to characterize the synthesized phosphors. The XRD results reveal that the fully crystalline pure LaAlO 3 phase can be obtained at 800 °C. The FE-SEM image indicates that the phosphor samples are composed of aggregated spherical particles with sizes ranging from 40 to 80 nm. Under the excitation of ultraviolet light (230 nm) and low-voltage electron beams (1−3 kV), the LaAlO 3:Tm 3+ and LaAlO 3:Tb 3+ phosphors show the characteristic emissions of Tm 3+ ( 1 D 2 → 3 H 6,4, 3 F 4 transitions) and Tb 3+ ( 5 D 3, 4 → 7 F 6,5,4,3 transitions), respectively. The CL of the LaAlO 3:Tm 3+ phosphors have high color purity and comparable intensity to the Y 2 SiO 5:Ce 3+ commercial product, and the CL colors of Tb 3+ -doped LaAlO 3 phosphors can be tuned from blue to green by changing the doping concentration of Tb 3+ to some extent. These phosphors have potential applications in area of field emission displays.